New flavonoids and methylchromone isolated from the aerial parts of Baeckea frutescens and their inhibitory activities against cyclooxygenases-1 and -2

In the present study,we carried out a phytochemical investigation of the ethanol extract of the aerial parts of Baeckea frutescens,which resulted in the isolation of two new flavonoid glycosides,myricetin 3-O-(5’-O-galloyl)-α-L-arabinofuranoside(1),6-methylquercetin 7-O-β-D-glucopyranoside(2),one new methylchromone glycoside,7-O-(4’,6’-digalloyl)-β-D-glucopyranosyl-5-hydroxy-2-methylchromone(3),together with three known compounds(4-6).The structures of these isolated compounds were established on the basis of 1 D and 2 D NMR techniques and chemical methods.The anti-inflammatory activities of the compounds 1-6 were evaluated for their inhibitory effects against cyclooxygenases-1 and-2 in vitro.Compounds 1-6 showed potent COX-1 and COX-2 inhibiting activities in vitro with IC50 values ranging from 1.95 to 5.54 μmol·L-1and ranging from 1.01 to 2.27 μmol·L-1,respectively.